Pressure-responsive device



Oct. 21, 1930. R. GRANT PRESSURE RESPONSIVE DEVICE Filed Aug. 20, 1927 Patented Oct. 21, 1930 UNITED STATES PATENT oFncE ROBERT GRANT, OF CICERO, ILLINOIS, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK PRESSURE-RESPONSIVE DEVICE Application filed August 20, 1927. Serial No. 214,223.

This invention relates to pressure responsive devices, and more particularly to a safety pressure relieving device for a pressure medium transmission line.

The primar object of this invention is to provide a sa ety pressure relieving device which is immediate and certain in its action and uniformly effective for automatically relieving excess pressure developed in a pressure medium transmission line. I

In accordance with one embodiment, this invention contemplates a device employing a hardened steel die cooperating with a fragile soft metal diaphragm backed by a spring pressed plunger of predetermined reaction, which upon the development of an excessive or abnormal pressure ruptures and permits a pressure to develop on a surface of a second spring pressed plunger having a relatively greater area than the surface of the first plunger, the second plunger being backed by a diaphragm of greater strength than the first diaphragm, which also ruptures, thereby accelerating the relieving of the pressure in-the associated pressure line. Fatiguing of the first diaphragm, which is of less strength than the second diaphragm, due to normal pressure conditions, is minimized by limiting the movement thereof toward its associated plunger to the point of its resting lightly on a reduced surface of the plunger, the immediate portion of which is of a constant diameter, to maintain it in an undistorted, level plane. 4

Other objects and advantages of this invention will more fully appear from the following detailed description taken in connection with the accompanying drawing, in which Fig. 1 is a diagrammatic illustration of a hydraulic compressor connected to a lead extrusion press used to sheath telephone cables and an interconnecting hydraulic transmission line with one embodiment of this invention inserted therein;

Fig. 2 is a vertical sectional view of the safety pressure relieving device embodying this invention;

Fig. 3 is a fragmentary view of Fig. 2 upon the diaphragms being ruptured, and

Fig. 4 is a horizontal section taken on the line 4-4 of Fig. 2. 1

Referring now to the drawing in detail wherein like reference numerals indicate similar parts, particularly Fig. 1, a hydraulic compressor 10 is connected to a lead sheath extrusion hydraulic press 11 by a header, pipe or line 12, which discloses one application of the safety pressure relieving device. In the lead sheathing of telephone cables the ram (not shown) of the press 11 is actuated by hydraulic pressure furnished by the compressor 10, such pressure may be six thousand pounds per square inch or more. For a more detailed illustration and description of a hydraulic press of the type referred to herein, reference may be had to Patent 1,583,814 to H. R. Till, dated May 11, 1926. Whatever pressure used, it is necessary to prevent an excess pressure being formed or transmitted to protect the compressor, the pressor the interconnecting line. An abnormal increase in the hydraulic pressure may be caused, for example, by the ram of the press 11 striking a solid stop, in whichcase the Water pressure may rise to a dangerous point in a tenth of a second and it 1s therefore necessaryin order to protect the various apdepression or chamber 17 formed at the top of the housing is a passage 18. Positioned in the aperture 15 adjacent its lower end, with the upper surface thereof flush with the lower wall of a horizontally disposed portion of the passage 18, is an apertured hardened steel die block 21, the aperture thereof being circular and flared inwardly from its upper to its lower end, as shown at 22. Threaded into the a rture 15 of the housing 14 below the die b ock 21 is a nip le 23, the lower end thereof being threa ed into the header, pipe or line 12'intercon'necting the compressor 10 and the press 11 (Fig. 1). The upper end of the nipp e 23 is shouldered and machined to provide a surface 24 which lies parallel with the adjacent lower end surface of the die block 21, which is also machined. Clamped between the parallel surfaces of the die block 21 and the nipple 23 is a fragile soft metal diaphragm 25 which serves to normally close or seal the passage 18 from the line 12. Having a sliding fit within the portion 16 of the die block aperture 15 is a hardened steel plunger 28 having a diameter which closely fits the restricted lower end of the flared aperture of the die block 21 and in its normal position. as shown in Fig. 2. the lower end surface thereof restsfiush without pressure upon the diaphragm 25, thus forming a support for the portion of the diaphragm extending across the small end of the die block aperture and maintaining the diaphragm in a perfect plane without any deleterious strain or distortion. To position in this manner the lower end surface of the plunger 28 it is provided at its upper end with a circular head 29, the under surface of which rests upon an annular surface 30 of the housing 14 along the aperture 15, thus predeterminedly posltioning normally the lower end surface of the plunger within the aperture of the die block.

Threaded onto the upper end of the housing 14 is a cap 31 provided with an internal annular machined surface 32 which lies parallel with the end annular surface of the housing 14. which is also machined. Clamped between these machined surfaces is a fragile soft metal diaphragm 33, the diameter and strength of which is greater than the diaphragm 25, the purpose of which will be made apparent as this description progresses. Bearing upwardly upon the lower surface of the diaphragm 33 is a plunger 36, which closely fits the diameter of the chamber 17, a

a reduced lower portion 37 of the plunger closely fitting the aperture 15. Carried in the aperture 15 and bearing upon the o posed upper and lower surfaces of the hea 29 of theplunger 28 and portion 37 of the plunger 36, respectively, is a compression spring 38 of predetermined reaction which normally maintains the plunger head 29 in contact with the surface 30 of the housing 14 and the upper surface of the plun er 36 in contact with the lower surface of t e diaphragm 33. Threaded into the cap31 is a pipe 39, which may be connected to a drain for disposing of the water passing into the chamber 17 when an excess pressure is developed in the line 12 in the application of the device 13 as illustrated. v

The operation of the safety pressure relieving device hereinbefore described is as follows: A spring 38 of a predeterminedreaction which is adapted to counter-balance the normal hydraulic pressure to be used to operate the press 11, is selected and mounted in the housing as hereinbefore described, along with suitable diaphragms 25 and 33, a diaphragm 33 being selected, which is strong enough to resist the force or reaction of the spring 38. As long as the hydraulic pressure contained in the line 12 is normal or within the prescribed limits, the plungers 28 and 36 and the associated diaphragms 25 and 33, respectively, will assume the position as shown in Fig. 2. Immediately upon an abnormal pressure being developed in the line 12, due to any cause, the force of the spring 38 will be overcome, due to the column of water, which acts as a punch, pressing upon the lower surface of the diaphragm 25, the upper surface of the diaphragm lying flush against the under surface of the plunger 28 which is closely fitted in the restricted lower end of the flared aperture of the die block 21, as hereinbefore described. This pressure it will be apparent will instantaneously deform the soft metal diaphragm 25 to such an extent that a complete rupture or shearing thereof will occur, as clearly shown in Fig. 3, thus unsealing the restricted entrance through the flared aperture of the die block 21 to the passage 18, whereupon the sudden release of the compressed column of water through the flared aperture quickly fills the passage 18 and is directed instantaneously upon the comparatively large area of the annular lower surface of the plunger 36 in the chamber 17. It will be readily understoodthat pressure is still being exerted upon the plunger 28 by the pressure medium, which pressure through the spring 38 is transmitted to the plunger 36. The increased force exerted upon the diaphragm 33, as just described, causes its severance or rupture and thus the pressure medium will freely escape from the line 12 through the aperture of the die block 21, the passage 18, chamber 17 and the pipe 39, where it is directed to the drain or other suitable receiving means, the plunger 36 and sheared portion of the diaphragm 33 coming to a rest against the inner horizontal surface of the cap 31, as clearly shown in Fig. 3. Thus all possibledamage of the compressor 10, press 11 and line 12 upon the pressure rising to an abnormal predetermined point likely to cause damage, is entirely eliminated. Tore set the safety device 13 after a release of an abnormal pressure in the line 12 it is merely necessary to disconnect the pipe 39 leading to the drain which may be very simply done, as will be readily understood, thereafter removing the device 13 as a whole from the upper threaded end of the nipple 23 and then removing the cap 31 from the housing 14,

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thus providing access to the ruptured diaphragms and 33. The ruptured dia phragms are then removed and replaced with others, the latter diaphragms being placed upon the upper surfaces of the nipple 23 and the plunger 36, the cap 31 is then replaced and the whole device is then threaded onto the nipple 23, thus completing the resetting of the device as shown in Fi 2.

Although this invention has been isclosed and described as applied to a particular apparatus wherein water is preferably used as the pressure medium, it is clear that it may have a more general application and is not necessarily limited to the relieving of excess hydraulic pressure, but is equally adapted to function regardless of the type of the particular pressure medium being used. Also it is clear that modifications can be made in the device without departing from the spirit and scope of the appended claims.

What is claimed is:

1. In a safety pressure relieving device, a housing having an inlet and an outlet port, a plunger supported in the housing, means for limiting the forward movement of the plunger, a fragile means for normally closing the inlet port and bearing lightly against a surface of the plunger, the immediate portion of which is of a constant diameter, and additional means separate and apart from said plunger and responsive to the movement thereof due to a predetermined pressure and normally closing the outlet port for establishing communication between the ports.

2. In a safety pressure relieving device, a housing having an inlet and an outlet port- 7 and a passageway extending therebetween, a

plunger supported in the housing, means for limiting the forward movement of the plunger, a fragile means for normally closing the inlet port and bearing lightly against a surface of the plunger, the immediate portion of which is of a constant diameter, and additional fragile means normally closin the passageway between ports and actuate by the movement of the plunger due to an excessive pressure to permit passage of the pressure medium between the ports.

3. In a safety pressure relieving device, a housing having an aperture, plunger means mounted therein providing a plurality of parallel surfaces adapted to be successively acted upon by a pressure medium, means for limiting the forward movement of the plunger means, the plunger means comprising a plurality of separated members, and a plurality of fragile means retaining the plunger means in operative position and responsive to a predetermined pressure for accelerating the movement of the plunger means for establishing an exit for the pressure medium from the housing.

4. In a safety pressure relieving device, a housing having an aperture of a varying diameter, plunger means mounted therein providing a plurality of surfaces of different areas adapted to be successively acted upon by a pressure medium, one of the surfaces fitting closely within a restricted ortion of the aperture, means forlimiting t e forward movement of the plunger means, the plunger means comprising a pluralit of separated members, and a plurality o fragile means retainingcthe plunger means in operative position and responsiveto a predetermined pressure for accelerating the movement of the plunger means for establishlng an exit for the pressure medium from the housing. 1

5. In a safety pressure relieving device, a housing having an aperture,.operatively connected plungers mounted therein providing a plurality of surfaces of different areas adapted to be successively acted upon by a pressuremedium, means for limiting the forward movement of the plungers, fragile diaphragms engaged by the plungers, one of the fragile diaphragms bearing lightly against the plunger surface of smaller area, the immediate portion of which is of a constant diameter, responsive to a predetermined pressure for communicating the pressure to the plunger surface having the larger area which is backed by another diaphragm in turn responsive to the pressure for accelerating the movement of the plungers for establishing an exit for the pressure medium from the housing.

6. In a safety pressure relieving device, a housing having an aperture of a varying diameter, apair of spring pressed plungers mounted therein providing a plurality of surfaces of different areas adapted to be successively acted upon by a pressure medium, one of the surfaces fitting closely within a restricted portion of the aperture, means for limiting the forward movement ofthe plungers, a fragile diaphragm operatively associated with each of the plungers, one of the diaphragms bearing against the plunger surface of smaller area, responsive to a predetermined pressure for communicating the pressure to the plunger surface having the larger area which is backed by another dia phragm of greater strength than the latter diaphragm in turn responsive to the pressure for accelerating the movement of the plungers for establishing an exit for the pressure medium from the housing.

7. In a safety pressure relieving device, a housing having an aperture providing a flared inlet and an outlet port and a passage connecting a restricted portion of the aperture intermediate the ports with the outlet port, a pair of plungers mounted in the aperture. each having a surface adapted to be successively acted upon by a pressure medium, one of the surfaces, the immediate portion of which is of constant diameter, fitting closely within the flared inlet port, a spring mounted in the aperture intermediate the plungers for maintaining them in a normal predetermined position, means for limiting the forward movement of the plungers, a fragile diaphragm operatively associated with each of the plungers. one of the diaphragms responsive to a predetermined excess pressure of the medium to cause movement of its associated plunger to shear the diaphragm and establish a passage for the medlum to cause a movement of the plunger of the largest diameter to shear its associated diaphragm whereby a passage is opened for the escape of the medium through the outlet port of the housing.

8. In a safety pressure relieving device, a housing having an inlet and an outlet port with a. connnunicating passage therebetween disposed at one side of the longitudinal axis of the housing, a plunger disposed coaxially within the housing and normally entered in the inlet port, fragile means for normally closing the inlet port and bearing against a surface of the plunger, and additional means adjacent the outlet port normally serving to prevent communication between the passage and the outlet port and responsive to the movement of the plunger due to a predetermined pressure for establishing communication between the ports.

9. In a safety pressure relieving device, a housing having an inlet and an outlet port and a passage extending therebetween, a diaphragm extending across the passage in a position adjacent to the outlet port, a diaphragm extending across the passage in a position adjacent to the inlet port, and a plunger means resiliently disposed between thediaphragms and cooperating therewith to effect a passage between the inlet and outlet ports at a predetermined pressure.

10. In a safety pressure relieving device, a housing having an inlet and an outlet port,

a plunger supported in the housing. means for limiting the forward movement of the plunger. a fragile means normally closing the inlet port and bearing against a surface of the plunger. and a diaph 'agm normally closing the outlet port and actuated by the movement of the plunger due to an excessive pressure to permit passage of the pressure medium between ports.

In witness whereof. I hereunto subscribe 5 my name this 10th day of August, A. D. 1927.

ROBERT GRANT. 

